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Wednesday, June 22, 2011

A Darkness Descending: Fungus Continues to Devastate Bats

Reprinted with permission from the Valley News. Not to be reproduced or distributed. Photo courtesy of Scott Darling.

By Krista Langlois
Valley News Staff Writer

Norwich -- Eight years ago, Russell Coney built a bat box outside of his home in Unity.
"I've got quite a bit of standing water," he said. "So I've got a big mosquito problem."
The solution seemed simple enough: build a wooden box, hang it about 12 feet off the ground and wait for bats -- which famously eat half their body weight in insects every night -- to move in and take care of business.
But in eight years, the bats never came: "Not a single one," Coney said, shaking his head.
Coney's mosquito problem might become more widespread if white nose syndrome, which has been swiftly decimating the Northeast's cave-dwelling bat populations since 2007, continues its devastating sweep across Vermont and New Hampshire. To date, anywhere from 76 percent to 99 percent of little brown bat and northern long-eared bat populations have been wiped out in Vermont, said state wildlife biologist Scott Darling, and the problem is comparable in New Hampshire.
Ginny Kiely has witnessed the decline firsthand. She used to see bats swooping from the sky outside her rural home in Quechee every night in the summer. But now? "We just don't have them anymore," she said.
"We're wondering what's going to happen with the insect population," chimed in Kiely's friend, Jeanette Veverka. "That's the big question."
Darling agrees. "Everyone wants to know the biological consequences of (white nose syndrome), including me, but we don't," he said in a talk in Norwich on Monday night called Bats in the Balance.
"It's probably going to be a factor for us with insect issues."
After 11 years of studying bats, Darling says he and other biologists don't yet understand what the repercussions will be if the little brown bat goes extinct, as might occur in only 15 years, experts warn. The little brown bat was once the most common of Vermont's nine species.
Even without white nose syndrome, it's difficult for bats to survive in northern latitudes, Darling explained. Some New England species migrate south in winter, but for species that overwinter in caves here, "if you only weigh three pennies, how do you do that?" Darling asks. "They're already living on the edge up here. Food disappears mid-November and doesn't come back until mid-April."
And because their reproduction rate is relatively low (one pup a year), declines in bat populations are particularly hard to recover from.
"If mice or rabbits were to get white nose syndrome, we'd have a problem on our hands, but we'd be able to reproduce them," said Darling, who has studied many animals during his 30 years as a wildlife biologist. But for bats, the problem is more dire.

Just a few years ago, South Strafford's Elizabeth Mine was the second-largest bat hibernacula, or overwintering cave, in New England.
Using a special net at the cave's exit, Darling has studied the population of bats in Elizabeth Mine over the past decade. In 2002, an average of 58 bats were trapped exiting the cave there every hour. In 2006, that number peaked at 163. But after white nose syndrome became prevalent, the numbers plummeted.
In 2008, there were 25 bats per hour. In 2009: zero.
"The Elizabeth Mine (population) has collapsed," Darling said. "We were able to observe the kind of mortality that has not been seen anywhere else in the country."
Other population studies have shown similar declines. And though the disease struck New York and Vermont first, Darling says he's identified 25 species of bats nationwide that could be susceptible.
"There are huge fears of it going to Carlsbad Cavern," where tremendous bat populations exist and the result could be devastating, Darling said.
As Darling and his colleagues went to work three years ago studying the white powdery substance found on the noses of the dying bats, they began making discoveries that could one day help prevent the disease's spread south and west.
First, they discovered the white substance was a cold-loving fungus, later named Geomyces destructans.
"(The bat) is almost an animal that was made for fungal infection. ... It meets lots of other bats (to easily spread the fungal spores) and then hibernates in dark, damp areas (where the spores thrive)," Darling said. "Generally a fungus does not kill its host," but somehow, this one does. It does not affect humans.
Nobody knows how the fungus found its way into the caves; some hypothesize it came in on human caving gear, or that it was carried on a bat from Europe to the United States. Bats in northern European countries have been found to have the same fungus, but it doesn't kill them there, though the populations are much lower to begin with. Or did they decrease long ago, due to the fungus? Biologists don't know.
But when strands of the European fungus were introduced in the lab to New England bats, the bats died quickly.
Similarly, Darling and his colleagues brought a group of healthy, uninfected little brown bats from Wisconsin and released them in an empty Vermont cave. The Wisconsin bats developed the fungus while hibernating and died within a few weeks, Darling said, suggesting the fungus is spread from the cave environment, not only from one bat to another.
While scientists have yet to find a treatment for white nose syndrome, they're experimenting with a number of potential solutions, including moving hibernating bats to fungus-free underground military bunkers and closing off hibernacula to determine how long the fungus lasts without its host. They've considered other ideas, such as fumigating the caves, but have decided against such potentially harmful measures for the moment.
And the little brown bat and the northern long-eared bat will soon be on the Vermont state endangered species list as well, if Darling's efforts are successful.
"While it's been a crisis, it's also been almost a blessing because people's awareness and appreciation of bats has really changed in three years time," he said.
Meanwhile, Darling says, homeowners might take several steps to help, including managing land to include large dead and dying trees for non-cave-dwelling bats to roost in, and "putting the tennis rackets away," referring to the anti-bat implement of choice.
You can also build a bat house for animals recently banished from an attic, so they don't just relocate to your less-sympathetic neighbor's house.
Darling also said that when excluding bats from your home, calling a professional who can install one-way doors is a good option, but wait until after August to do so -- from May to August, bats are having pups, and sealing them off may further harm the population. The best time to seal off entrances is in the winter, if no bats are present; or from September to October if they are.
Darling is not currently looking for volunteers at this time, though he may be in the future. Already, groups of trappers, Boy Scouts and public service employees have embarked on bat house building campaigns after hearing Darling speak, and he said that such efforts are welcome and very useful.
"That's the kind of response Vermonters are giving, and that's what helps me get up every morning and go at it every day," he said.
Krista Langlois can be reached at klanglois@vnews.com or 603-727-3305.
On the Web
* Bat Conservation International: www.batcon.org
* Vermont Fish and Wildlife: www.vtfishandwildlife.com

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About Me

I'm Krista. I write stories about the intersection of people, places and nature. Formally, I'm a contributor at High Country News, a non-profit environmental news magazine once called "a scrappy institution that produces some of the finest journalism in the American West." My work has also been published in Slate, Orion, Alaska magazine, New Zealand Wilderness magazine, the Denver Post, Adventure Journal, and a number of other newspapers and websites. See more at www.kristaleelanglois.com.